The present invention relates to thermoset epoxy waterproofing membranes comprising one or more epoxy resin(s), a liquid amine terminated polyamide, optional polyamine(s) and/or optional filler(s). The membrane may also include hydrocarbon solvents, water or other viscosity-reducing media.
Over time, numerous materials have been used to prevent water penetration for roofs, bridges, parking decks, water-retention ponds, swimming pool liners, basement water barriers, land fills, secondary containment, geomembranes and ponds. In the past, in the area of roofing, materials such as terracotta, slate, metals, asbestos shingles, tar paper, tar and gravel and built up asphalt layers have been used. The problem is that in many instances, these materials proved to be bulky and heavy thereby increasing the static load for the structure.
In addition, ponds and pits for disposal of wastes of chemical plants, petroleum refineries, power plants and mining installations use liners to insure against seepage of aqueous wastes. Traditionally, these liners have consisted of two membrane types, elastomeric and thermoplastic. A common elastomeric membrane is vulcanized EPDM and a thermoplastic membrane is plasticized PVC. Both membrane types have advantages and disadvantages. Vulcanized EPDM has outstanding resistance to outdoor weathering, good cold flexibility, high strength and excellent elongation. Its major disadvantage is the necessity of using adhesives for sealing the membrane seams to provide a continuous leak-free covering. Such adhesives are expensive and time-consuming to apply and are prone to delaminate under stressful conditions because of their low strength. This leads to leaks. Plasticized PVC offers surer seams because the material, being thermoplastic, can either be heat-sealed or solvent-welded to give an integral seam of high strength. Such membranes, however tend to lose plasticizer with time resulting in shortened useful life and poor cold crack resistance.
In the roofing art, the term xe2x80x9cflat roofxe2x80x9d refers to a roof having a slope of less than about 25xc2x0 relative to a horizontal plane. Many such roofs are substantially flat with a slight incline to allow water to run off. Some flat roofs comprise numerous sloping sections which create peaks and valleys, and a water drain is generally located to the bottom of each valley to facilitate water drainage. Flat roof traditionally comprise three components (from top to bottom): (1) a waterproof membrane (top); (2) thermal insulation (middle); and (3) the structural deck (bottom).
The flat roof waterproof membrane typically comprises two or more plies of a felt membrane in combination with bitumen (generally coal tar pitch or asphalt). The felt stabilizes and strengthens the bitumen, and distributes tensile stresses when the bitumen is cold and glasslike. Alternatively, the membrane can be a polymeric sheet or a series of polymeric sheets adhered together to form seams where they are joined.
The membrane is typically used in combination with metallic and/or nonmetallic flashings which guard against leakage through portions of the membrane which are pierced or terminated, such as at gravel stops, walls, curbs, expansion joints, vents and drains.
Mineral aggregates (normally gravel, crushed rock, or slag) are often spread atop the membrane to hold it down on the roof deck and protect the membrane from wind, rain, solar degradation and fire. Such aggregate may be unnecessary on smooth-surfaced asphalt roofs having glass-fiber felts.
Conventional membranes cannot resist large movements of the deck or insulation, and will be punctured by heads of fasteners which protrude above the insulation due to such movements. Membrane puncture (due to fastener heads, foot traffic or the like), excessive membrane shifting or movement (due to foot traffic, wind forces or the like) and seam failure are primary causes of leaks in properly installed flat roofs.
Many systems have been devised for providing a roof covering for buildings. One method uses pieces of water-impervious material, such as slate or wood, layered upon the roof in overlapping rows so that each joint is covered by the piece layered above it. Such shingled roofs are satisfactory when the roof is pitched at a high angle so that there is no tendency for the water to flow back through the cracks between the pieces. Even in these cases, when located in areas where freezing occurs, ice occasionally forms on the lower edges of roofs to form a dam which forces water back through the cracks into the interior of the building.
A method of covering low slope roofs that did not have cracks in them was evolved making use of asphalt as an impregnate and bonding agent along with felts of various fibers. The asphalt in the form of a hot liquid or an emulsion was spread over the roof, then pieces of asphalt impregnated felt were rolled out over it. Another layer was then applied moving the location of the seams so that they did not occur in the same area. Built up roofs can be used when the roof was of a low pitch or flat as there were no cracks for water to back up through. The built up roofs fail due to cracks developing because of exposure to weathering and embrittlement of the felt, oxidation of the asphalt, and expansion and contraction of the system because of temperature changes. During cold weather, the asphalt becomes brittle and easily cracks due to expansion and contraction forces.
U.S. Pat. No. 4,827,686 discloses a roofing membrane comprising at least two calendared layers of a cured or uncured compounded flexible rubber, said membrane having at least on its weather side an adherent, cured, pigmented non-staining, durable and flexible coating of from about 0.002xe2x80x3 to 0.020xe2x80x3 thick of an epoxy resin. As noted in column 3, lines 1-5, the possibility of pinholes is avoided by using at least two calendared layers of the flexible rubber as the membrane. The roofing membrane is then painted with an epoxy resin coating rather than the prior art coatings such as chlorosulfonated polyethylene in order to prevent staining and improve durability.
Therefore, it would be highly desirable to have a thermoset epoxy waterproof membrane which overcomes the problems associated with the prior art membranes.
The present invention relates to thermoset epoxy waterproofing membranes comprising:
(a) one or more epoxy resin(s) having an average of at least 1.5 epoxy groups per molecule;
(b) a liquid amine terminated polyamide prepared by reacting at least one C18-50 dicarboxylic acid and an aminoalkylpiperazine in a ratio of moles of aminoalkylpiperazine to equivalents of carboxyl group in the acid of greater than 0.75:1;
(c) one or more optional polyamine(s);
(d) one or more optional filler(s); and
(e) one or more optional modifying resin(s)
wherein the tensile modulus of the thermoset epoxy waterproofing membranes is less than 200,000 psi and the tensile elongation of the thermoset epoxy waterproofing membranes is greater than 20%.
The thermoset epoxy waterproofing membranes are useful for preventing water penetration on roofs, bridges, parking decks, water-retention ponds, swimming pool liners, basement water barriers, land fills, secondary containment, geomembranes and ponds. The thermoset epoxy waterproofing membranes may be used as the original waterproofing system or to replace or repair existing waterproofing systems. These membranes remain flexible over their lifetime, maintain waterproofing properties with use and provide environmental protection while being resistant to water and chemicals thereby providing an extended service life.